Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 772 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
5. 5.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
6. 6.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a small bowl (d) white paper
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
9. 9.True or false: plugging in the iron is a job for an adult. (a) True (b) False
10. 10.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a balloon (c) an adult with an iron (d) white paper
12. 12.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
13. 13.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
14. 14.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
15. 15.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
16. 16.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
17. 17.True or false: yeast is needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) an adult with an iron (d) a cotton bud
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the ironing time (d) the iron setting
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) white paper (d) a small bowl
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the same cotton bud
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) yeast (d) turmeric powder
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
27. 27.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) lemon juice (d) an adult with an iron
31. 31.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
32. 32.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) any child (d) only an adult
33. 33.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
34. 34.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
35. 35.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
37. 37.True or false: white paper is needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a balloon (d) a magnet
40. 40.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True

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